The following application proposes to study the development of the nervous system in Drosophila melanogaster. The major objectives are to generate behavioral marker substitutes for histochemical markers of nervous system genotype, to carry out an autoradiographic analysis of the development of the larval and adult nervous systems, to assay for the existence of developmental compartments in the central nervous system and other internal tissues by the use of genetic mosaics, to characterize anatomically, developmentally, functionally and genetically particular mutants which seem to effect synapse formation between eye and brain, and to characterize the interactions in space and time which lead to normal or abnormal eye-brain wiring.